1. Field of the Invention
The present invention relates to a medical drive device that is attached to a medical apparatus to move a tip side of the medical apparatus.
2. Description of the Related Art
In the medical field, endoscopes are in wide use for the observation of the inner parts of specimens. Such an endoscope includes an operation unit, and an insertion unit that is inserted into the specimen. An imaging element such as a CCD is accommodated in a tip portion of the insertion unit, and an image captured by the imaging element is displayed on a monitor.
To deal with the difficulties of the endoscope insertion operation, an endoscope driving device that assists the insertion (propulsion) of the endoscope which has a tip driven unit driven by a motor and attached to the tip side of the endoscope by moving the tip driven unit is known. For example, WO2009/114137A2 discloses an endoscope propulsion auxiliary device in which a bag-shaped rotating body (toroid) is used as the tip driven unit and the rotating body is pinched and moved in a circulating manner by a driving wheel driving the motor and a driven roller. The rotating body rotates in contact with an inner wall of the digestive tract, such as the colon, of the specimen, for example, a human body, and the tip side of the endoscope moves forward into the digestive tract.
Also, JP2008-093029A discloses a self-propelled rotation-type endoscope system in which a rotating housing that is formed of a metallic plate member wound in a spiral shape to have flexibility is attached in a rotatable manner to the insertion unit of the endoscope via a mouthpiece and the rotating body is rotated to move the insertion unit forward. The rotating housing rotates in contact with the inner wall of the digestive tract, and thus propelling force is given in the insertion direction to the insertion unit of the endoscope. In this manner, the insertion of the endoscope can be facilitated even in a highly curved digestive tract such as the colon.
In JP2008-093029A, load on the motor increases and the rotating speed decreases to decrease the propelling force of the rotating housing when the friction between the rotating housing and the inner wall of the digestive tract increases due to, for example, the strong pressing of the rotating housing against the inner wall of the digestive tract. In this case, propulsion by the rotating housing cannot be performed. Therefore, in a case where the rotating speed of the motor decreases, the current supplied to the motor is increased to make up for the decrease in the rotating speed by increasing the rotating speed of the motor. In this case, motor torque increases. The motor torque is detected by a motor driver, and a detected torque value is compared to a preset limit torque value. In a case where the detected torque value is larger than the limit torque value, the supply of the current to the motor is stopped to stop the driving of the motor while a warning is generated by a buzzer or a warning light to suppress the failure of the motor by the excess torque. Further, frequent stopping of the motor is prevented by varying the limit torque value.
Also, in JP2008-093029A, the rotating housing has flexibility so as to be deformed along with the deformation of a flexible tube of the endoscope and is configured of a long tube which has approximately the same length as the insertion unit of the endoscope. Therefore, there is a case where the torsion of the rotating housing itself causes the rotating speed of the tip portion to be lower than the rotating speed of a base end portion. Even in this case, the rotating speed of the motor increases and the motor torque increases.